Remote Data Monitor For Heart Pump System

ABSTRACT

A pump control system includes a controller module for controlling a pump, such as an implantable blood pump. A remote monitor is adapted to communicate with the controller module via a wireless communications medium, such as a low-power radio s frequency link. The remote monitor provides a user interface similar or identical to the controller module, providing a user the ability to remotely monitor the pump&#39;s performance and to respond to alarms.

CROSS REFERENCE TO RELATED APPLICATION

This application claims the benefit of U.S. Provisional PatentApplication No. 60/522,874, entitled “REMOTE DATA MONITOR FOR HEART PUMPSYSTEM,” filed on Nov. 16, 2004, which is incorporated by reference.

BACKGROUND

The invention relates generally to heart pump systems and, morespecifically, to a remote monitor for such pumps.

Implantable blood pump systems are generally employed either tocompletely replace a human heart that is not functioning properly, or toboost blood circulation in patients whose heart still functions but isnot pumping blood at an adequate rate. Known implantable blood pumpsystems are primarily used as a “bridge to transplant.” In other words,existing blood pump system applications are mainly temporary fixes,intended to keep a patient alive until a donor is available. However,the shortage of human organ donors, coupled with improvements in bloodpump reliability make long-term, or even permanent blood pumpimplementations a reality.

Despite this need, existing implantable pump systems have not beensatisfactory for long term use. Known systems of the continuous flowtype are designed primarily for use in a hospital setting. These systemstypically include the implanted pump device, a power source such as arechargeable battery, a motor controller for operating the pump motor,and an external operator console. While some existing implantable pumpsystems allow for operation while decoupled from the operator console,operating these systems “stand-alone” can be a risky endeavor. This isdue, at least in part, to the lack of an adequate user interface whenthe system is decoupled from the console.

Moreover, prior blood pump systems are not conducive to long-term useoutside an institutional setting. Known systems often require a large,fixed operator console for the system to function. While prior artoperator consoles may be cart mounted to be wheeled about the hospital,at home use of known systems is difficult at best. Other problems ofprior pump systems that have limited their mobility and use torelatively short times are related to motor controller size and shapelimitations.

Thus, there is a need for a pump control system that addresses theshortcomings associated with the prior art.

SUMMARY

In accordance with certain teachings of the present disclosure, a pumpcontrol system includes a controller module for controlling a pump, suchas an implantable blood pump. A remote monitor is adapted to communicatewith the controller module via a wireless communications medium, such asa low-power radio frequency link. The remote monitor provides a userinterface similar or identical to the controller module, providing auser the ability to remotely monitor the pump's performance and torespond to alarms.

BRIEF DESCRIPTION OF THE DRAWINGS

Other objects and advantages of the invention will become apparent uponreading the following detailed description and upon reference to thedrawings in which:

FIG. 1 is a block diagram of a pump system in accordance with teachingsof the present disclosure.

FIG. 2 illustrates an exemplary implantable heart pump in accordancewith an embodiment of the system disclosed herein.

While the invention is susceptible to various modifications andalternative forms, specific embodiments thereof have been shown by wayof example in the drawings and are herein described in detail. It shouldbe understood, however, that the description herein of specificembodiments is not intended to limit the invention to the particularforms disclosed, but on the contrary, the intention is to cover allmodifications, equivalents, and alternatives falling within the spiritand scope of the invention as defined by the appended claims.

DETAILED DESCRIPTION

Illustrative embodiments of the invention are described below. In theinterest of clarity, not all features of an actual implementation aredescribed in this specification. It will of course be appreciated thatin the development of any such actual embodiment, numerousimplementation-specific decisions must be made to achieve thedevelopers' specific goals, such as compliance with system-related andbusiness-related constraints, which will vary from one implementation toanother. Moreover, it will be appreciated that such a development effortmight be complex and time-consuming, but would nevertheless be a routineundertaking for those of ordinary skill in the art having the benefit ofthis disclosure.

Turning to the figures, and in particular to FIG. 1, a ventricle assistdevice (VAD) system 10 in accordance with an embodiment of the presentinvention is illustrated. The VAD system 10 includes components designedto be implanted within a human body and components external to the body.The components of the system 10 that are implantable include a pump 12and a flow sensor 14. The external components include a portablecontroller module 16 and a remote monitor module 18. The implantedcomponents are connected to the controller module 16 via a percutaneouscable. The controller module 16 may be mounted to a support device, suchas a user's belt 23 or to a vest worn by the user, for example.Additional components of a VAD system are shown and described in U.S.Pat. No. 6,183,412, which is incorporated by reference.

The controller module 16 includes a processor, such as a microcontroller80, which in one embodiment of the invention is a model PIC16C77microcontroller manufactured by Microchip Technology. Themicrocontroller 80 includes a multiple channel analogue to digital (A/D)converter, which receives indications of motor parameters from the motorcontroller 84. Thus, the controller module 16 may monitor parameterssuch as instantaneous motor current, the DC component or mean value ofthe motor current, and motor speed.

The embodiment shown in FIG. 1 further includes an integral flow meter86. At least one flow sensor 14 is implanted down stream of the pump 12.Alternately, a flow sensor 14 may be integrated with the pump 12. Theflow meter 86 is coupled between the implanted flow sensor 14 and themicrocontroller 80. The flow meter 86 receives data from the flow sensor14 and outputs flow rate date to the microcontroller 80, allowing thesystem to monitor instantaneous flow rate.

The VAD System 10 may incorporate an implantable continuous-flow bloodpump, such as the various embodiments of axial flow pumps disclosed inU.S. Pat. No. 5,527,159 or in U.S. Pat. No. 5,947,892, both of which areincorporated herein by reference in their entirety. An example of ablood pump suitable for use in an embodiment of the invention isillustrated in FIG. 2. The exemplary pump 12 includes a pump housing 32,a diffuser 34, a flow straightener 36, and a brushless DC motor 38,which includes a stator 40 and a rotor 42. The housing 32 includes aflow tube 44 having a blood flow path 46 therethrough, a blood inlet 48,and a blood outlet 50.

The stator 40 is attached to the pump housing 32, is preferably locatedoutside the flow tube 44, and has a stator field winding 52 forproducing a stator magnetic field. In one embodiment, the stator 40includes three stator windings and may be three phase “Y” or “Delta”wound. The rotor 42 is located within the flow tube 44 for rotation inresponse to the stator magnetic field, and includes an inducer 58 and animpeller 60. Excitation current is applied to the stator windings 52 togenerate a rotating magnetic field. A plurality of magnets 62 arecoupled to the rotor 42. The magnets 62, and thus the rotor 42, followthe rotating magnetic field to produce rotary motion.

The remote data monitor (RDM) 18 is a small portable handheld devicethat includes a processing device 112 and a user interface 110 thateffectively replicates the user interface 111 of the controller module16 remotely via a wireless communication link 120. In an exemplaryembodiment, the wireless link 120 is a low-power radio frequency (RF)link usable over a maximum distance of approximately 300 feet (100meters) using the system's standard antenna configuration. While in use,the device provides the user with the ability to remotely monitor theVAD pump's 12 performance and to respond to alarms. The pump controller16 and remote monitor(s) 18 may be programmed via the clinical dataacquisition system or the remote monitor 18 may be programmedtelemetrically by the pump controller 16, for example.

The wireless link 120 includes antennas, which my suitably comprisesimple monopoles. The system's antennas maybe constructed from ferriterods or with traces on the system's internal printed circuit board.Integral antennas may be used exclusively, or external antennas may beemployed for increased range capability, or a combination of integraland external antennas may be used.

The integrity of the link 120 will be continuously verified while thedevice is in operation. In the event that the remote monitor 18 islocated too far from the VAD controller 16, the RF link becomes “noisy”or unusable, or if the monitor's 18 batteries are low, the VADcontroller 16 will continue to function and alarm normally. Morespecifically, in exemplary implementations, the remote monitor 18periodically transmits status information back to the pump controller 16to conform proper link operation. The remote monitor 18 may monitor anddisplay received signal strength information, and the pump controller 16can increase or decrease its transmitter output power proportional tothe signal strength reported back from the remote monitor 18.

The carrier may be angle modulated (i.e. frequency modulated (FM) orphase modulated (PM)) to minimize the effects of external noise inducederrors. Alternatively, the carrier may be amplitude modulated (AM) tomaximize battery life. Forward error correction techniques may be usedto maximize the integrity of the communication link. Spread spectrumtechniques are used to further minimize externally induced noise fromcompromising the communication link between the pump controller andcorresponding remote monitor. The receiver may request that atransmission be retransmitted in the event of an error. In typicalinstallations, transmissions are within the US and European ISM (i.e.Industrial, Scientific, Medical) band.

Multiple controller 16 and remote monitor 18 pairs may be used in closeproximity to one another. Each pump controller 16 and correspondingremote monitor 18 may communicate on a designated frequency or frequencypair or on the same frequency or frequency pair. Transmitted datapackets contain the address of the intended remote monitor 16. Each pumpcontroller 16 first “listens” to confirm if another pump controller 16is transmitting. In the event there is no other transmission, the pumpcontroller 16 may begin transmitting and, conversely, in the eventanother transmission is “heard” the pump controller 16 will wait for thechannel to be clear. In other implementations, one pump controller 16may broadcast to several remote monitors 16 (e.g. one with the patient,one with the caregiver).

The data transmitted between the pump controller 16 and remote monitor18 may be encoded such that the remote monitor 18 only responds to datatransmitted with a unique address or to transmissions containing thecorrect address. A hardware or software based correlator may be used toidentify the address.

In certain embodiments, the remote monitor 18 is approximately 3 incheswide by 2 inches high by 1 inch thick, weighs less than 5 oz., includesa wrist-strap such that it may be worn by the caregiver or patient onthe wrist, and includes a combination belt clip/tilt stand for use onthe patient's or caregiver's belt or nightstand. The device 18 may bepowered from an internal rechargeable battery to be completely portableor it may be plugged into the ac mains using an optional power adapter.Additionally, the device 18 may be plugged into an automotive poweroutlet for continuous operation while on long trips in an automobile orairplane. The device 18 will support simultaneous charging of theinternal battery while monitoring the VAD controller 16 (e.g. at nightwhile patient and parent/caregiver are sleeping).

The remote monitor's 18 user interface is identical to the VADcontroller 18 interface and includes a tricolor light emitting diode(LED) backlit graphic liquid crystal display (LCD) to displaymulti-lingual diagnostic and emergency messages, a sealed two-buttonkeypad with tactile feedback and rim-embossing to silence alarms andscroll through diagnostic message displays, three bicolor LEDsindicating individual battery status and fail-safe mode operation, twodistinct, variable pitch, variable loudness audible enunciators, and anoptional audible voice output for diagnostic and emergency alarms.

The backlit LCD can indicate functional pump information to the patientand/or caregiver, and in exemplary embodiments, the backlight utilizesmultiple colors to convey functional and alarm information to thepatient and caregiver (e.g. green=normal, yellow-diagnostic alarm,red=emergency alarm).

The audible alarms may be elicited through piezo buzzer enunciators. Thevariable loudness audible enunciators maybe be operated such that thepitch and/or volume changes proportionally to the length of time thatthe alarm is activated. The audible voice output may be elicited througha voice coil type speaker element. A natural language speech synthesizermay be employed, including a phoneme based speech synthesizer enablingaudible speech to be generated in a multiplicity of languages. Further,the natural language voice's pitch and cadence may be programmed tosimulate a male or female adult voice based on the patient orcaregiver's preference. Still further, the natural language voiceoutput's pitch and cadence may be programmed to simulate aless-intimidating child's voice for pediatric cases. A motor withintegral eccentric may be enabled to vibrate during any alarmingcondition to help in alerting the patient or caregiver.

Optionally, in pediatric applications, a wireless audio channel may beadded to integrate the functionality of a commercial “baby monitor” intothe system. A transmitter with a microphone or other sound detectingdevice transmits audio signals to a receiver integrated into the remotemonitor 18, which further includes an output device such as a speaker.This minimizes the number of different systems the parent or caregivermust use and manage. This function would also include a volume controlto allow the parent or caregiver to set the device's output to thedesired audio level.

The above description of exemplary embodiments of the invention are madeby way of example and not for purposes of limitation. Many variationsmay be made to the embodiments and methods disclosed herein withoutdeparting from the scope and spirit of the present invention. Thepresent invention is intended to be limited only by the scope and spiritof the following claims.

1. A pump control system comprising: a controller module connectable toan implanted heart pump; and a monitor module adapted to communicatewith the controller module via a wireless communications medium.
 2. Thepump control system of claim 1, wherein the controller module includes:a processor; a motor controller electrically coupled to the processor,the motor controller adapted to power the pump motor such that the pumpmotor operates at a desired speed, the motor controller adapted tooutput digital representations of pump motor operating parameters to theprocessor; a user interface coupled to the processor; and wherein themonitor module includes a user interface.
 3. The pump control system ofclaim 1, wherein the controller module user interface matches themonitor module user interface.
 4. The pump control system of claim 1,wherein the wireless communications medium is a bi-directional radiofrequency (RF) fink.
 5. The pump control system of claim 1, whereinmonitor module includes a device for attaching to a user's wrist.
 6. Thepump control system of claim 1, wherein monitor module includes a devicefor attaching to a user's belt.
 7. The pump control system of claim 1,wherein monitor module includes a device for receiving and outputtingaudio signals.
 8. The pump control system of claim 1, wherein monitormodule is programmed to periodically transmit status information to thecontroller module.
 9. A method of operating a blood pump, comprising:connecting a controller module to a blood pump; and transmitting databetween a monitor module and the controller module via a wirelesscommunications medium.
 10. The method of claim 9, transmitting dataincludes transmitting functional and alarm messages.
 11. The method ofclaim 9, further comprising: powering the pump such that the pumpoperates at a desired speed; outputting digital representations of pumpoperating parameters on a user interface of the controller module;transmitting the pump operating parameters to the monitor module; anddisplaying the pump operating parameters on a user interface of themonitor module.
 12. The method of claim 9, wherein transmitting dataincludes transmitting via a bi-directional radio frequency (RF) link.13. The method of claim 9, further comprising: attaching the monitormodule to a user's wrist.
 14. The method of claim 9, further comprisingattaching the monitor module to a user's belt.
 15. The method of claim9, further comprising transmitting status information from the module tothe controller module.
 16. The method of claim 15, wherein transmittingstatus information includes transmitting received signal strengthinformation.
 17. The method of claim 16, further comprising varying thetransmit output power of the controller module in response to thereceived signal strength information.
 18. The method of claim 9, whereina plurality of controller modules are connected to a plurality ofcorresponding blood pumps, and wherein one monitor module communicateswith the plurality of controller modules.
 19. The method of claim 9,wherein a plurality of controller modules are connected to a pluralityof corresponding blood pumps, and wherein each of the controller modulescommunicates with a corresponding monitor module on a predeterminedfrequency.
 20. The method of claim 19, wherein data transmitted from thecontroller module includes the address of the intended monitor module.21. The method of claim 9, wherein a plurality of monitor modulescommunicate with a single controller module.
 22. The method of claim 9,wherein the controller module verifies that no other controller moduleis transmitting before transmitting data to the monitor module.